A number of techniques have been utilized in the past to make constituent identifications in atherosclerotic lesions. These techniques include HPLC, NMR chemical-shift imaging and immunocytochemistry. Atheroma recognition has been performed by other techniques including duplex ultrasound and pneumoplethysmography. Atheroma classification has been made by microscopic and histologic examinations. Additionally, spatial profiling has been accomplished by chemical analysis, enzymatic assays and immunofluorescence techniques.
While all of these different techniques and technologies are useful in qualitatively analyzing atherosclerotic lesions and plaques in vitro, it should be appreciated that new technologies used for treating atherosclerotic lesions and plaques require a reliable method of in vivo lesion and plaque recognition to be most effective. A need therefore exists for a reliable apparatus and method for the chemical examination of arterial endothelium and, more particularly, for analyzing the composition of atherosclerotic lesions and plaques in living tissue.